Use the Belt/Chain assembly feature to model systems of belts and pulleys or chains and sprockets.
The
Belt/Chain assembly feature creates:
- Belt mates to constrain the relative rotation of the pulley components.
- A sketch containing a closed chain of arcs and lines describing the path of the belt.

The software calculates the length of the belt based on the positions of the pulleys. Optionally, specify the length of the belt and have the pulley positions adjust (at least one pulley must have an appropriate degree of freedom).
You can select to automatically create a new part containing the belt sketch and add the part to the assembly. In the part file, use the sketch as a sweep path to create a solid belt.
You can also create belts using blocks in sketches.